A UN peacekeeping force may be sent to Central African Republic in September to support the African Union and French troops trying to maintain control there. Here, a Democratic Republic of the Congo soldier stands guard near a barracks in the town of Bria. (Goran Tomasevic/Reuters)

The UN Security Council is set to vote Thursday on whether to send 12,000 peacekeepers to the Central African Republic, where sectarian violence has claimed thousands of lives.

During a visit to Central African Republic last weekend, UN Secretary General Ban Ki-moon said French forces who have been trying to control the violence have been "overwhelmed." He warned the crisis, centred in the capital Bangui, could turn into another genocide like Rwanda if the international community doesn't step in.

Navi Pillay, the UN's human rights chief, said the violence between Muslim and Christian militias has reached "a terrifying level."

On Wednesday alone, another 30 people were killed as militia groups exchanged gunfire in the town of Dekoa, many of whom were civilians hit by stray bullets, the BBC reported. The UN estimates 2,000 people have been killed since December.

Meanwhile, over 15,000 Muslims remain trapped in Bangui where they're being protected by French and African soldiers the UN said.

There are an estimated 2,000 French soldiers and 6,000 African Union troops in Central African Republic now. The UN said a potential peacekeeping mission could begin as soon as September.

The U.S. ambassador to the UN backed the idea during a trip to Central African Republic on Wednesday, though so far the U.S. has declined to send any of its soldiers to the country.

Ambassador Samantha Power, making her second visit to the country since violence erupted in December, said the African peacekeeping mission is now working to fill the gap left by neighbouring Chad. Last week the Chadian government began withdrawing its 850 troops following allegations some had indiscriminately killed dozens of unarmed civilians.

Power, who met Wednesday with top officials from the African peacekeeping force, said that Cameroonian and French forces were being moved into the areas previously guarded by the Chadians.

"There's no question that we need to redouble our efforts," she told reporters.

"But this adds even more urgency to the task of getting more troops and more police deployed rapidly in order to fill those gaps which really do exist."

Central African Republic exploded into violence in early December amid mounting resentment toward a Muslim rebel government that had seized power in March 2013 by overthrowing the president, who'd been in power for a decade. The rebel leader-turned-president had little control over his forces, who were blamed for raping, torturing and killing civilians, particularly among the country's Christian majority.

Once the government fell in January, Christian militia fighters began attacking Muslim civilians in retaliation, prompting tens of thousands to flee the country and leaving an untold number dead. African peacekeepers have helped protect and evacuate many civilians under threat, though in some cases they have stood by as mobs slaughtered people accused of having collaborated with the rebels.

At least 22 African peacekeepers and three French soldiers have been killed in Central African Republic since December.